Fascinating topic.
There's alot of things that we are yet to explain scientifically, and I've experienced "high strangeness", including a drug induced psychosis for which I was sectioned. (Not of my own doing, a complicated situation involving an unusual reaction to anti-depressants, being spiked and a highly stressful personal situation which essentially resulted in a nervous breakdown).
I am not religious at all, and wasn't brought up practising, but it was interesting that alot of my delusions centred around religious subject matter. Some of it clearly reflected things I had taken in from older family members who were essentially lapsed Catholics.
My enforced Section came about because after voluntarily agreeing to spending time as an inpatient, I then went for a walk and tried to walk on water from the beach near the hospital. I was rescued by windsurfers and then put on suicide watch although I really wasn't trying to harm myself - I was playing into a game I thought was going on around me.
Point is, the mind is a very powerful thing. I'm interested objectively in the occult and psychology, and it was very interesting the number of people I met in hospital who's delusions were also underpinned by some sort of religious theme. I was aware that what I was experiencing seemed both real but irrational. Anti-psychotics seemed to enhance, not dull the experience.
In esoteric circles, the phrase "as above, so below" is used, it comes from times when superstition and alchemy and religious oppression was rife. I suspect it means that our minds can construct a perceived reality through a combination of input throughout our lives, which, during existential crisis, when our senses are heightened, can more readily identify and attach significance to things which seem resonant.
So if one believes in demonic possession, we can manufacture that experience to a degree and our culture will mean that those around us familiar with the concept will almost share the delusion due to the recognition of it.
I don't know if I'm explaining it very well, and it's just my theory. It's also a useful way for an overburdened mind to let go of responsibility for things that are painful to accept possibly. Pinning it on an external force, and genuinely believing in it is a potent thing. People genuinely can't help it because the influence of their learned beliefs is so strong.
It's why I am passionately opposed to fear based religious teachings. In susceptible people, say with genetic predisposition to schizophrenia, being brought up to worship and fear an omnipotent entity who watches your every move is an absolutely disastrous recipe for paranoia, for a start. Think how many serial killers have said "the Devil made me do it" or similar. Some are psychopaths who may use it as a culturally ingrained defence quite cynically, and some genuinely believe it.
I find it odd that we never hear about "angelic possession" which would logically be the unproblematic counterpart.
I also find it interesting that there is apparently a documented uptick in religious revival being reported, which seems to reflect the growing instability in the world, where faith is being list in our secular systems due to very unsupernatural corruption etc.
Strange and interesting times indeed, and worthy of much examination in terms of the evolution of human psychology.